Roofing



March 29, 1955 w. w., ROWE 2,705,209

ROOFING Filed April 19, 1947 i y IN VEN TOR..

" U4/V Ml. 1.465 /fan/E.

ATTORNEYS.

United States Patent O 4 Claims. (Cl. 154-51) Cincinnati, Ohio, assignorto Inc., Lockland, Ohio, a corpo- This application is acontinuation-in-part of my copend ing application, Serial No. 389,961 ofthe same title, tiled April 23, 1941, now abandoned.

My invention pertains to roong in which the resistance of the structureto water and weather depends upon the use of bitumen or equivalentsubstance in a heavy, discrete layer serving as a waterproof membrane.

In the manufacture of current prepared roofing a dry felt, which is arelatively heavy, porous, felted sheet containing a considerablepercentage of rag iibers is saturated with a saturating type asphalt,then coated with a heavy continuous layer of a relatively non-saturatngtype asphalt.

Built-up rooting is similar in general structure except that it isassembled on the job. Saturated felt is nailed to a wooden deck or ismopped onto a concrete deck with hot asphalt; and a roof covering isbuilt-up in plies mopped together by means of a high melting pointasphalt. A top layer of the asphalt is also applied over the topmostlayer of felt. In each instance, the weather resistance and waterproofcharacter of the rooting is dependent upon the integrity and continuityof a relatively heavy layer of coating asphalt, or a plurality of suchlayers.

The coating of asphalt is not perfectly weather resistant, but issubject to a progressive deterioration. Under the influence of actiniclight and the weather, the surface of the asphalt takes on a hardcrusted condition, frequently referred to as an oxidized condition. Thehard external crust cracks or crazes along a `multitude of lines,exposing a fresh asphaltc surface at the cracks. This surface in turnbecomes hard and crusted, and a continuation of the cracking and crazingdeepens the cracks into canyons or valleys which eventually progressthroughout the thickness of the asphaltc layer.

Covering substances such as the crushed slate frequently applied toprepared roongs and the gravel frequently applied to built-up roongsdelay this action somewhat but do not prevent it. Since the utility ofthe rooting depends upon the integrity of a continuous, relatively heavylayer of asphalt or other bitumen, the result of this progressivedeterioration adversely affects the life of such roofing materials.

The principal object of my invention is the provision of a rootingfabric or roong structure which, while dependent for its effective lifeon the integrity of a heavy, continuous layer of bitumen or itsequivalent, is nevertheless not subject to the rapid and progressivedisintegration of such a layer n the manner described above, and hencehas much longer life. It is an object of one aspect of my invention toprovide protective means for rooting of otherwise conventional type toprevent or greatly delay the progressive destruction of the bituminouslayer. It is an object of other aspects of my invention to provideroofing fabrics which are not constructed like those heretofore known inthe art, but have novel and improved structures as will hereinafter beset forth. My invention is applicable to the provision of preparedroongs or substitutes for prepared roongs which may be applied in rollform or in the form of cut pieces such as shingles or strips. It is alsoapplicable to the production of prepared rooting materials orsubstitutes for them which may be employed on the job in theconstruction of so-called built-up roofs.

The invention is based upon my discovery that the association, with anotherwise exposed thick layer of bituminous substance or its equivalent,of an external web which is universally contractible and expansible i.e., readily stretchable and contractible in all directions, acts toprevent the cracking and crazing aforesaid and hence the progressivedeterioration of the said thick layer. The type of universallyexpansible web which I employ is one which has been gathered in aplurality of directions so as to be stretchable in all directions, andsuch a web is preferably formed by creping.

The weather resistance of the stretchable web by itself is not offundamental importance. While cloth may be employed, I have found thatcreped paper is sufcient as a covering layer, and when so used will addyears to the useful life of a rooting fabric. The universalstretchability is, however, a requirement, and webs which are notstretchable at all or are stretchable in but one primary direction willnot serve to prevent the progressive disintegration of the bituminouslayer.

Without wishing to be bound by theory, I nevertheless believe that thereason for the progressive disintegration of a bituminous layer inexposed rooting products, in View of the crusting action, is primarily amatter of expansion and contraction. The initial cracking or crazing ofthe so-called oxidized crust is due to expansion of the bituminous layeragainst the inexpansible crust. The expansion or contraction of a baseor support bearing the bituminous coating is not of primary consequencealthough it may to some extent affect the expansion and contraction ofthe bituminous layer. When the cracks have once been formed, furtheroxidation of the bituminous surfaces in the cracks, accompanied byfurther expansion and contraction, works the cracks down into the bodyof the layer until presently along the lines of the cracks the bodybecomes completely cut through and the base is exposed to the weather.

A covering imposed upon a heavy bituminous layer, insofar as it protectsthe surface of the bituminous layer from the weather, oxidation andactinic light, might be expected to prevent the formation of the initialcrust. But a non-expansible web, such as a web of plain paper or a webwhich is stretchable in but one direction', in adhesive union with aheavy bituminous layer, is itself subject to the expansion andcontraction of the bituminous layer and will split or crack in one or aplurality of directions if subjected to expansion and will lose bond ifsubjected to contraction. When these cracks are formed, the oxidation ofthe bituminous layer occurs in them, and the action of the progressivedeepening of canyons in the bituminous layer begins and continues to thecomplete destruction of that layer. This action s similar to thedestruction of the bituminous layer under such discontinuous coatings asslate, sand, gravel or the like. A web which is universally. expansible,however, follows the movements of the bituminous layer and does notitself crack. Hence, it not only prevents the formation of a generalcrust over the 'whole surface of the asphaltc layer, but prevents theformation of any exposed cracks which, being subject to crusting, couldprogressively deepen. It is further remarkable that an external layer ofuniversally stretchable paper, in intimate adhesive association with aheavy bituminous layer seems to acquire a property of relativeindestructibility from weathering. A piece of universally stretchablepaper which, exposed by itself or with'a thin coating of bitumen to theweather would rapidly disintegrate will, if associated throughout itsarea with a heavy, unitary layer of bitumen, retain for many years itsbond and hence a suficient integrity to protect that layer of bitumenfrom progressive disintegration, even though the paper is itselfdirectly exposed to the weather. It desired, however, the paper mayitself be protected by a paint which has in# herent elasticity or whichfollows the contours of the crepes.

In one aspect, it is an object of my invention to provide protection forhitherto known types of prepared roongs as aforesaid by providing inassociation with the normally exposed surface of a heavy layer ofbituminous substance, an external covering which is a universallystretchable web. In another aspect of my invention, it

. is my object to produce improved roofing fabrics by asf sociating twoor more heavy layers of bitumen with intermediate and externaluniversally stretchable webs.

I am awarethat multiple products comprising univer` sally stretchablewebs adhered together by coatings of asphalt, with or without interiorreinforcement, have been made in the art and have been used as buildingor wrapping papers. Because such papers have a certain degree of waterresistance they would, if attached to a roof, give temporary protectionagainst the Weather. Such products, however, have mented together withsuch amounts of bitumen as are required for plying purposes. Whensubjected to the weather the useful life of these materials is extremelyshort. The product tends to delaminate, and the stretchable paper websweather away and disintegrate. Because such bituminous coatings have noentity or integrity apart from the paper, they disintegrate physicallyalong with the paper. The structure in the course of time becomes apulpy mass and in effect washes away. Resistance to the Weather such asis required in a product serving the purposes of commercial roofing isdependent upon a layer of bitumen so thick as to act as an independentand discrete entity apart from any base or covering with which it isassociated. Such a layer of bituinen is, however, subject to its ownindependent ilow or movement and expansion and contraction and, in theunprotected state, to the progressive disintegration which has beendescribed and which it is an object of this invention to prevent orgreatly delay.

These and other objects of the invention, which will be clear from whathas been said above, which will be pointed out hereinafter, or whichwill be apparent to one skilled in the art upon reading thesespecications, I accomplish in the structures and arrangement of parts ofwhich I shall Vnow describe certain exemplary embodiments. i

Reference is made to the accompanying drawings, wherein:

Figure l is a partial cross-section of one type of roofing fabric madein accordance with my invention.

Figure 2 is a similar view showing an edge treatment thereof.

Figure 3 is a partial cross-sectional view of another type of rootingfabric made in accordance with my invention.

Figure 4 is a similar view showing an edge treatment thereof.

Figure 5 is a similar view showing edge treatment.

Figure 6 is'a partial cross-sectional view of a built-up roof Amade inaccordance with my invention.

Figure 7 is a diagrammatic elevational view showing an apparatus andmethod of providing seam forming means in connection with my rooting.

Figure 8 is a plan view of a piece of my rooting fabric showing seamforming means.

Figure 9 is a partial perspective view showing a mode of seam formation.

Figure 10 is a partial sectional view taken across the seam of Figure 9.

By a heavy discrete layer of bitumen, I mean a continuous layer of thesubstance of a thickness which enables it to leave its own mode ofexpansion, contraction, flow and movement irrespective of a support orcovering web. In the prepared and built-up rooiings of commerce, theasphalt coatings range approximately from lb. to lb. of the bitumen per100 square feet (or square of 108 sq. ft.) of the roofing fabric. Thesaturated felt employed will usually be from 15 to 30 pounds per square.While this is a weight ratio of around l: or in excess thereof, it willbe understood that the layer of bitumen is thick in the absolute sense.

In the manufacture of building papers, a coating of plying asphalt on apaper web will normally have a ratio of 1:1 or less; but because paperdoes not compare in thickness with saturated felt, the layer of asphaltwill be thin in the absolute sense.

In my products I associate a covering web of universally snetchablepaper with a layer of bitumen which in weight or thickness will have aratio to the paper of 3:1 or more in most instances. The independentilow action of a layer of bitumen will bear a relationship to thethickness of the paper; but in instances where a 3:1 or greater ratio isnot maintained (as where an exceptionally heavy paper is chosen withouta proportional increase in the another kind of consisted of thestretchable webs cebituminous layer) I do not employ a bituminouscoating less than about 8 lb. to l0 1b. per 100 square feet. It may bemade thicker with improvedresults, the upper limit being a thickness, inview of the characteristics of the bitumen itself, which might permitcreeping of the bituminous layer at high temperatures on a roof of thepitch for which a particular roofing is designed. The biturnen itselfshould be of the coating type as known in the rooting industry. Asatisfactory exemplary asphalt is one having a ball and ring softeningpoint of approximately 180-200 degrees F. and a penetration at 77degrees F., 100 grams, 5 seconds, of approximately 20 according to theA. S. T. M. standard.

The stretchable webs which I employ are webs of paper which have beencreped so as to be universally stretchable. Preferably, this is done inaccordance with the teachings of Patent 2,008,181 in the naine of Kemp.Any available papers meeting a standard of economy may be employed. Iordinarily employ kraft papers because of their availability andcheapness. The thickness of the webs may be considerably varied, and Iordinarily employ papers of between 15 1b. and 60 lb. basis weight.

It is important to bring the papers themselves into as intimate anassociation as possible with the surface of the discrete bituminouslayer. Hence, I prefer to employ papers creped with relatively fine anduniform creping crinkles as distinguished from papers of corrugated,

pleated or folded types wherein substantial areas of the f paper websmight be out of contact with the bituminous layer. Fine and uniformcreping crinkles, even with heavy papers, can be attained by creping thepapers by means of a positive creping adhesive. This adhesive may be thebitumen used for the discrete waterproofing layer in my roongs or it maybe some other substance capable of forming a good bond therewith andchosen for additional characteristics.

The exposed paper webs do not require to be waterproofed throughouttheir body since even plain paper webs directly exposed to the weatherin my products exhibit a long-term water resistance, as set forth above.But the durability of the paper webs may be increased and the tendencyto shrink may be decreased by saturating or coating them with protectivesubstances of bituminous, waxy, resinous, rubbery or othercharacteristics, and this may be done prior to or as an incident of thecreping operation.

In Figure l, I have illustrated a rooting fabric which, insofar as itembodies a base of saturated felt 1, and a heavy discrete layer ofbituminous coating 2, is similar to the prepared roongs of commerce.This product has, however, been treated by imposing upon the outersurface of the bituminous layer 2 a layer 3 which is a universallystretchable. gathered web, as set forth above. The addition of such aweb has been found to add years of service to the product in the waysalready described. The web 3 is the portion of the product directlvexposed to the weather. It mav, as indicated, be of untreated paperthroughout its thickness. but it may if desired be waterproofed orsaturated or colored or treated on the exposed surface with a coating ofpaint or lacquer or suitable binder containing metallic flakes, as inaluminum paint. Y

It has been found that the addition of such a laver protects thebituminous laver 2 from the progressive destruction which has beendescribed. Contrary to expectations. the web 3 does not tend to expandby itself upon standing or weathering. On the contrary. it tends tomaintain itself under slight tension. and if the roofing is exposed toweathering, including high temperatures, a tendency of the web 3 to pullslightly inwardlv from cut edges of the product mav be observed. Thereis no tendency, however. toward delamination providing the pitumisnouslayer 2 is well-bonded to the stretchable ayer The product illustratedin Figure 1 may be manufactured and sold in roll form or in the form ofcut individual units. In smaller units. such as shingles or shinglestrips, or even at the edges of roll rooting units. T may destroy thetendency of the web 3 to pull inwardlv and also protect the edge of thefelt by a method illustrated in Figure 2 where a stretchable web 3.larger in dimensions than the remainder of the rooting unit comprisingthe saturated felt 1 and the bituminous layer 2 has been employed, andwhere the extending edge of the web 3 has been brought around the edgeof the roofing unit 6 and cemented back underneath, as at 3a. Thecementing process. If the paper is creped so as to acquire 25% may bedone with bitumen or with any other waterstretchablity in eachdirection, 57% is added to the proof adhesive capable of making a goodbond. weight or thickness of the initial bituminous coating.

In Figure 3 I have shown a piece of rooting material Similarly, if thepaper is creped so as to acquire 33Va% manufactured entirely from aplurality of stretchable 5 stretchability in each direction, 77% will beadded to the webs and a plurality of discrete, heavy layers of bitumen.weight or thickness of the coating. These factors may The illustratedproduct comprises four layers of creped be taken into account inapplying the initial coating of paper 4, 5, 6 and 7, and three layers 8,9 and 10 of bitumen to the paper. Again, the thickness of thecoatcoating type bitumen. The product may, however, be ing betweenlayers of creped paper will, of course, be made of three layers of paperand two intermediate layers 10 doubled if the creped paper layers areplied with their of bitumen, or with a larger number of layers as maycoated sides next each other. In manufacturing products be desired. suchas are shown in Figure 3, I ordinarily form two In a product such as isillustrated in Figure 1, the layers of coated paper and adhesivelysecure them tosaturated felt 1 serves to provide a base or support forgether with the coated sides in contact. The resultant the bitumen, butis itself deficient in weather resistance. product will be of suflicientstrength and resistance to Moreover, the exemplary product has but onelayer of stretching to permit the application of a heavy coating bitumenwhich can serve as a waterproofing membrane, of asphalt for thereception of additional layers of coated although it may be made withmore by plying. By concreped paper. In making a 4-ply product, I mayiirst trast the product of Figure 3 contains in the illustratedmanufacture two 2-ply products, coat each and ply themembodiment threediscrete heavy layers of bitumen servtogether with their coated sides incontact.

ing as waterproofing membranes and providing a greatly In theapplication of built-up rooiings, my products prolonged life. The use ofa plurality of layers of bitupresent further advantages and economies.It will be men and intermediate and external layers of stretchableunderstood that the efcacy of a built-up roof if properly paper providesin itself a structure having suilicient body laid will depend upon thenumber of continuous waterand strength for roofing uses, yet containinga plurality proofing membranes which it contains. Since the upper ofbituminous layers capable of serving as a water and or surface membraneis subject to the distintegration weatherproof membrane. which I havedescribed, and since the saturated felt is Certain other advantages aresecured in such a prodnot itself satisfactorily weather resistant, it isthe general uct. The uSe of stretchable Webs on both Sides providespractice to cover all portions 0f a roof deck with a plu-' a productwhich not only is reversible in that it may be rality of layers ofsaturated felt, and intermediate layers laid either side up, but alsowill not stick when wound plus a top layer of mopped asphalt. Themopping of into rolls. The use 0f tale 0r other material fOr prelayersof felt onto a roof deck and onto each other is an venting adhesion iS0bviaied The PrOduCt, mOIeOVer, 1S arduous and inconvenient task, theresults of which are as a whole more exible than a prepared roofing ofthe greatly affected by the skill of the workman and weather samethickness and conventional construction. conditions. Moreover, theresult may be made unsatis- This makes it possible fOr me t0 effect aSeam c0nfactory by overheating the asphalt in the kettle wherebystruction aS hereinafter S'et forth. The Surfacing and its weatherresistance may be impaired and by failing to intermediate layers ofuniversally stretchable paper are apply the felt layer to a mopped-0ncoating at a time effective in Preventing Cracking 0f the product whenit when the asphait is sufficiently tacky to form a good is bellisharply al all auglewhen laid UPOn a 100f and 40 bond. Blisters inbuilt-up roofs are not uncommon.

fastened at both edgss 1l {naintains itself bodily unlel In laying abuiltp roof from a product such as illusslight tension which keeps it.taut and prevents buckling trated in Figure 3, it may be noted that theproduct alor stretching. Yet the tenSlOn 1S S0 Slight that 1t Will readycontains a plurality of bituminous membranes. 110i Pull aWaY fromfasienlngmeans such as roofing Halls, These were formed at the factoryunder conditions of nor will it pull itself into WrlnkleS- Y carefultemperature control. They will be more uniform It has further been foundthat if the :external layer and more dependable than membranes formed bymopof bitumen in a product Such aS Shown in Figure 3 beping on the job.Because of the plurality of membranes comes, through the removal ordestruction of the eX- built into my product, the laying of a built-uproof is posed layer 4 of stretchable paper, subject to progressivesimplified. Fewer layers and fewer moppings will be disintegrationCharacteristic 0f heavy bituminous layers, 50 employed, and it isusually suicient to use a single layer this disintegration will stop assoon aslit reaches an of a product of suitable thickness. Thus n Figure6 I underlying layer of stretchable paper, again very greatly have shownadjacent pieces 12 and 13 of my product prolonging the life of theproduct. mopped onto a concrete deck 14 with a suitable cemented Whilethere is no tendency toward delamination in lap as at 15. It will beunderstood that on a wood deck the product, the Same phenomenon 0f theSlight pulling 55 fastening means, such as nails, will be employed tohold back of the upper paper layer 4 at the edges of the prodan edge ofone piece which edge including the fastening uct may be encountered andcan be corrected in a similar means will then be lapped by an edge ofthe adjacent way. In Figure 4 I have shown the product where the piece.A,

upper paper layer 4 has been caused tofextend beyond 'It will not benecessary to provide my built-up roof a cut edge and has been foldedover, brought back bewith a top mopping of bitumen. If, however, theroof neath the product, as at 4a, and adhesively secured as is tosustain tratlic,:it may be desired to top mop it, as at before. Yetanother way of treating the edges of the 16 in Figure 6, and to provideit with a covering of product is shown in Figure 5 where an edge portiontheregranular material, as at 1' 7. This may be done without of has beenbodily bent back upon itself.l and adhesively detriment to the roof orits weather resistance.

secured at 11. This is a treatment which may be used The extraordinaryflexibility of my products such as both for roll rooting and forindividual units such as shown in Figmre V13 makes possible theformation of shingles which may if desired be rolled or turned on allvarious types of adhesively united seams. In Figure 8 exposed edges, itbeing unnecessary to do this at the end I have shown at 18 a p iece ofmy fab'ric prepared for of the product which will be lapped by othershingles seam formation. The sid e of the fabric shown is that or units.The turned edges may merely be adhesively which will be the under .sidein use. Along one edge I secured or they can if desired be held by anysuitable provide a band 19 of suitable waterproof adhesive mafasteningmeans such as rivets, staples, or the like. terial. This material may be a pressure-sensitive, sol- In manufacturing a product such asillustrated in Figvent-sensitive or thermoplastic adhesive of waterproofures 3 to 5, I prefer to crepe the paper by means of the nature. Asphaltis an entirely satisfactory. material. bitumen to be used as thewaterproofing membrane. I When used, it may be applied hotand'immediately covhave given above thicknesses of bitumen capable ofservered with a strip 29 of cellophane .or similar material. ing as thediscrete heavy layers contemplated by this It is characteristic of thiscombination that the celloinvention. In accordance with the teachings ofmy Patphane or similar non-fibrous ilm may readily be removed ent No.1,782,767, dated November 25, 1930, entitled from the band of adhesiveby a quick jerkingmovement, Creping Process, it is not diicult to crepepapers bearalthough with a suitably tenacious asphalt, it is not capaingasphaltic or other bituminous layers of the required ble of beingreadily peeled away. It may be removed by thicknesses. It will beunderstood however that coatings peeling if it its iirst wet with water.Removal by a jerkf r cre in are usuall im osed u on the lain paper; ingmovemen is mos convenien hcence tihe gthickness of] thepcoatingp'isincregsed by the At the other edge of the fabric 18, I p rovide anotheramount of gathering imparted to the paper in the creping band of similaradhesive but of lesser width, as at 21.

This is also covered with a strip 22 of cellophane or the like. Inwardlyof the edges of the adhesive bands 19 and 21, I prefer -to score thematerial `to facilitate bending.

The material of Figure 8 maybe made continuously asindicated in Figure7. Here the material, moving in a direction of the arrow, is firstpassed between rotary scoring devices 23 and 24, and is next coated withthe adhesive. This maybe done by providing a pan 25 of asphalt or othersuitable material (together with heating means as may be required), anapplicator roll 26 and a series of transfer rolls 27. An anvil roll 28may be employed to support the fabric during the coating.

Coating may be applied to form the strips 19 and 21 in other ways. Byway of example, it is within the scope of my invention to spray onto thesurface of the fabric 18 a heat softened bitumen or other adhesive, orto apply by spraying an artificial latex or dispersion of such material.The cover strips, one of which is indicated at 22 at Figure 7, arewithdrawn from rolls as at 29 and applied by squeeze rolls 30 and 31.The product treated in this fashion may be wound into suitable rolls forshipment.

In laying the product, theside to which the adhesive has been applied isdisposeddownwardly, but the edges are turned up on the score lines andthe cover strips 20 and 22 are removed. In Figure 9 I have shown twoadjacent pieces of roofing at 32 and 33. The edge portions areturned upas at 34 and 35 and are brought together with their coated sides incontact. A completely tight seam may be formed between these juxtaposededges' by pressing them together, with an application of heat ifrequired to reactivate the adhesive, or with an application of solvent.The pressing may be done by rollers 36 and 37 mounted on pivoted arms 38and 39 by which the rollers may be pressed strongly together and bywhich they may be moved along the seam. It will be noted as an advantageof this procedure that the edges of the fabric are pressed directlytogether and thus are brought into positive contact. This is to bedistinguished from an operation in which the edges of roofing fabric aremerely lapped and are pressed against a roof deck. In such an operationinequalities in the roof deck may relieve the pressure over certainareas, interfering with full contact.

After a seam has been made as illustrated to the right in Figure 9, theentire standing portion of the fabric may be laid over as shown at theleft-hand end of the ligure. Because the portion 34 of the fabric isnarrower than the portion 35, it will be seen that a coated edge of thefabric piece projects freely and may be used to fasten the laid-overseam construction against the fabric piece 32. Adhesion may be effectedby running a pressure roller 40 along the edge of the seam formation,out the application of heator solvent as may be required.

lwith or with- Prior to the laying over of the standing seamconstruction, the marginal portions of the fabric piece 32 may befastened to the roof deck, if ofv wood, as by fastening nails or thelike 41 in Figure 10.

The fabric 18 may be prepared with covered lines of adhesive for theformation of other types of seams as will now be evident.

Modifications may be made in my invention without departing from thespirit of it. Having thus described my invention in certain exemplaryembodiments, what I claim as new and desire to secure by Letters Patentis:

1. A prepared roofing fabric consisting lof a plurality of heavy,continuous, discrete layers of `bituminous substance, each capable ofserving as a waterproof membrane, and each having a weight of not lessthan about 8 to 10 pounds per sq. ft., said layers being separated fromeach other by universally stretchable creped webs of paper 1nintimateladhesive association therewith, there being layers ofuniversally stretchable crepe paper forming the outer surfaces of thefabric, and means for the formation of 'seam structures in adjacentfabric pieces, said means comprising a coating of adhesive substance ona marginal portion of the rooting fabric, said coating being covered bya removable protective strip.

2. The structure claimed in claim 1 wherein the fabric is scored forbending along a line adjacent to the edge of said coating.

3. The structure claimed in claim 1 wherein the fabric is scored forbending along a line adjacent to the edge of said coating, and in whichsaid adhesive comprises bitumen, and said covering is a removable stripof nontibrous film substance.

4. T he structure claimed in claim 1 prepared for seam formation andbearing strips of adhesive adjacent oppo- `site marginal edges of thereverse face of the fabric, said strips being of unequal width.

References Cited-in the le of this patent UNITED STATES PATENTS

1. A PREPARED ROOFING FABRIC CONSISTING OF A PLURALITY OF HEAVY,CONTINUOUS, DISCRETE LAYERS OF BITUMINOUS SUBSTANCE, EACH CAPABLE OFSERVING AS A WATERPROOF MEMBRANE, AND EACH HAVING A WEIGHT OF NOT LESSTHAN ABOUT 8 TO 10 POUNDS PER 100 SQ. FT., SAID LAYERS BEING SEPARATEDFROM EACH OTHER BY UNIVERSALLY STRETCHABLE CREPED WEBS OF PAPER ININTIMATE ADHESIVE ASSOCIATION THEREWITH, THERE BEING LAYERS OFUNIVERSALLY STRETCHABLE CREPE PAPER FORMING THE OUTER SURFACES OF THEFABRIC, AND MEANS FOR THE FORMATION OF SEAM STRUCTURES IN ADJACENTFABRIC PIECES, SAID MEANS COMPRISING A COATING OF ADHESIVE SUBSTANCE ONA MARGINAL PORTION OF THE ROOFING FABRIC, SAID COATING BEING COVERED BYA REMOVABLE PROTECTIVE STRIP.